1. Field of the Invention
The present invention relates to a power transmission device used in, for example, a compressor in a vehicle air conditioning device.
2. Description of the Related Art
A generally known compressor used in a vehicle air conditioning device includes a hollow compressor body, a compression section that compresses a fluid sucked into the compressor body, and a drive shaft connected to the compression section, and is adapted so that the drive shaft is rotated by power of an engine to drive the compression section and suck and discharge refrirerant.
A known power transmission device provided in the compressor includes a pulley rotated by power from an engine, a transmission member rotated by the pulley, and a hub connected to the transmission member via a torque limiter, and is adapted so that a plurality of protrusions provided in the pulley and the transmission member so as to be circumferentially spaced apart and axially protrude face circumferentially each other, a block-shaped shock absorbing rubber is placed between each protrusion of the pulley and each protrusion of the transmission member, and torque of the pulley is transmitted to the transmission member via each shock absorbing rubber (for example, see Japanese Patent Publication No. 2001-65595).
For the power transmission device, when a rotation number change occurs between the pulley and the transmission member, the torque of the pulley is transmitted to the transmission member while the shock absorbing rubber between the protrusions is elastically deformed in a compression direction to absorb a shock, but compression forces repeatedly applied to the shock absorbing rubber may cause the shock absorbing rubber to be permanently deformed in the compression direction, thereby creating a clearance between the shock absorbing rubber and each protrusion. Thus, in the case where power is transmitted from a drive source such as an automobile engine where periodical rotation number changes occur, the clearance may cause vibration in a rotation direction or collision noise, or an inertial force of the transmission member in a rotation area that is not subjected to shock absorbing action of the shock absorbing rubber may cause an excessive shock on the transmission member at the time of an abrupt rotation number change.